Sodium potassium stimulated adenosine triphosphatase has been found to decrease in response to dextroamphetamine in normal volunteers. This is similar to a decrease found in the depressed state. Specific binding of the ion pump blocker ouabain was measured in red cells and lymphocytes. We were unable to confirm reports that incubation in a low potassium medium should increase numbers of binding sites, and we are not pursuing this work. The calcium pump co-factor protein calmodulin has been measured in cerebrospinal fluid of control and euthymic bipolar patients. No difference has been found in the groups.